Comparison of the optimisation and linear sequential method for tuning of multiple PSSs

The system stability is becoming an increasingly important issue in the deregulated power systems. Locally tuned controllers however, may not be able to meet the demands for robust stability of the system with increased level of uncertainties and coordinated tuning of large number of controllers is becoming necessary. Various optimisation based methods for coordinated tuning of controllers had been reported in the literature in the past and discussed separately. This work compares three commonly used forms of the objective function for coordinated tuning of PSSs to determine the effectiveness of the optimisation procedure. In addition, the optimisation-based method (s) are compared with the linear sequential method (based on the residues of the open loop transfer function) for coordinated tuning of PSSs. Both methods are tested on a four-machine two-area system developed in Matlab/simulink environment. The methods are compared in terms of ease of tuning, effectiveness and duration of the tuning procedure.